Back to EveryPatent.com
| United States Patent |
5,707,749
|
|
Katagiri
, et al.
|
January 13, 1998
|
Method for producing thin film multilayer wiring board
Abstract
A thin film multilayer wiring material excellent in reliability, yield,
productivity, and higher positioning accuracy includes an insulation
organic film having a wiring pattern on one surface and an adhesive layer
on another principal surface. The insulation organic film is a polyimide
film having a heat resistance at a pyrolysis beginning temperature of
350.degree. to 550.degree. C., a dielectric constant of 3.5-2.2 and a
flame retardance of V-0 or V-1 according to the UL-94 standard. The
adhesive layer contains an ether bismaleimide compound.
| Inventors:
|
Katagiri; Junichi (Ibaraki-ken, JP);
Takahashi; Akio (Hitachiota, JP);
Nagai; Akira (Hitachiota, JP);
Akahoshi; Haruo (Hitachi, JP);
Fujisaki; Kouji (Hitachi, JP);
Mukoh; Akio (Mito, JP);
Kobayashi; Fumiyuki (Sagamihara, JP)
|
| Assignee:
|
Hitachi, Ltd. (Tokyo, JP)
|
| Appl. No.:
|
494974 |
| Filed:
|
June 26, 1995 |
Foreign Application Priority Data
| Current U.S. Class: |
428/473.5; 29/852; 174/259; 174/266; 428/354 |
| Intern'l Class: |
B32B 007/12; B32B 027/00 |
| Field of Search: |
428/473.5,209,354,355
29/830,852
174/259,266
156/253,280
219/121.7,121.71
|
References Cited
U.S. Patent Documents
| 3436819 | Apr., 1969 | Lunine | 29/625.
|
| 4933045 | Jun., 1990 | DiStefano et al. | 156/630.
|
| 5055343 | Oct., 1991 | Murphy | 428/209.
|
Other References
Jap-A-2-45998; Feb. 15, 1990 Hitachi K.K.
J.P.-A-2-94594 Apr.05, 1990 Hitachi Ltd.
|
Primary Examiner: Zirker; Daniel
Attorney, Agent or Firm: Antonelli, Terry, Stout, & Kraus, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a Divisional application of application Ser. No.
08/097,060, filed Jul. 27, 1993 now abandoned, which application is a
Continuation-In-Part application of Ser. No. 07/800,078, filed Nov. 29,
1991 (now abandoned).
Claims
What is claimed is:
1. A thin film multilayer wiring material which comprises an insulation
organic film having a wiring pattern layer on one principal surface and an
adhesive layer on another principal surface; said insulation organic film
being a polyimide film having a repeating structure represented by the
following formula:
##STR7##
wherein X represents an aromatic diamine residue and the adhesive layer
contains an ether bismaleimide compound represented by the following
formula:
##STR8##
wherein R.sub.1 represents a hydrogen atom, a lower alkyl group or a lower
fluoroalkyl group, R.sub.2 represents a hydrogen atom, a lower alkyl group
or a lower fluoroalkyl group, m represents an integer of 1 to 4, and
R.sub.3 and R.sub.4 each represents CH.sub.3 or CF.sub.3 and may be
identical with or different from each other.
2. A thin film multilayer wiring materiel according to claim 1, wherein the
insulation organic film comprises a polymer having a heat resistance at a
pyrolysis beginning temperature of 350.degree.to 550.degree. C., a
dielectric constant of 3.5- 2.2, and a flame retardance of V-0 or V-1
according to the UL-94 standard.
3. A thin film multilayer wiring material according to claim 1, wherein the
insulation organic film has a thickness of 1 to 100 .mu.m.
4. A thin film multilayer wiring material according to claim 1, wherein
line thickness and line width of the wiring pattern formed on one surface
of the insulation organic film are both 10 to 40 .mu.m.
Description
BACKGROUND OF THE INVENTION
This invention relates to a thin film multilayer wiring board, a method for
producing the same and an insulation organic film for use in the thin film
multilayer wiring board.
Hitherto, multilayer wiring boards have been produced by sequential
lamination, i.e. by sputtering a conductor metal to form a pattern, then
forming an insulation film thereon, making through-holes through the
insulation film, and again forming a conductor metal layer (JP-A-2-94594).
Furthermore, a thin film multilayer wiring board prepared by laminating
films having wiring patterns on both sides through adhesive films is
proposed (JP-A-2-45998).
in the above-mentioned sequential lamination, steps of forming wiring
patterns, forming an insulation film and forming through-holes must be
successively carried out, and although the sequential lamination is
distinguished in accuracy of circuit wiring, yield is low and a long time
is required for the production, which are serious problems in the
improvement of lamination productivity. As a means for improving the
yield, it is proposed to laminate films having wiring patterns on both
sides through adhesive films. However, the proposed lamination method has
also a serious trouble in the improvement of reliability of multilayer
wiring boards, because it is difficult to position the wiring pattern
layers with high accuracy, as compared with the sequential lamination.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for producing a
thin film multilayer wiring board distinguished in its reliability which
is capable of solving the yield problem with good productivity and of
improving a positioning accuracy of wiring pattern layers.
The gist of the present invention will be explained below.
The first aspect of the present invention is to provide a method for
producing a thin film multilayer wiring board. That is, the method
according to the first aspect of the present invention comprises a step
(A) of positioning an insulation organic film having a wiring pattern on
one surface in proximity to a substrate for a multilayer wiring board on
which a circuit is provided, thereby aligning the wiring pattern of the
insulation organic film with the circuit on the substrate and bonding,
through an adhesive layer, another principal surface of the insulation
organic film to the substrate and a step (B) of forming through-holes
through the insulation organic film and the adhesive layer, a step (C) of
making the through-holes conductive by plating, a step (D) of bonding,
through an adhesive layer, the surface layer obtained in the step (C) to a
principal surface of an insulation organic film having a wiring pattern on
another surface, and a step (E) of positioning the wiring pattern on the
insulation organic film used in the step (D) to the surface circuit layer
obtained in the step (C) for making connection therebetween and forming
through-holes through the insulation organic film and the adhesive layer,
at least one run of the above steps (C), (D), and (E) being repeated.
The second aspect of the present invention to provide a method further
comprising repeating at least one run of a step (F) of bonding, through an
adhesive layer, a surface of an insulation organic film (a first layer)
having a wiring pattern on another surface to a surface of an insulation
organic film (a second layer) having a wiring pattern on one surface on
which another layer is to be formed, a step (G) of positioning the wiring
pattern of the first layer to the wiring pattern of the second layer for
making connection therebetween and forming through-holes through the
insulation organic film of the first layer and the adhesive layer, and a
step (H) of making the through-holes conductive by plating, thereby
forming a thin film multilayer wiring material having a plurality of
wiring pattern layers, then bonding, through an adhesive layer, a
substrate to one principal surface of the thin film multilayer wiring
material on which the wiring pattern layers are not formed, positioning
the circuit on the substrate to the wiring pattern layers of the thin film
multilayer wiring material for making connection therebetween and forming
through-holes therethrough, and bringing the through-holes into an
electrical connection.
The third and fourth aspects of the present invention comprise carrying out
the methods of the first and second aspects of the present invention with
the thin film wiring material comprising an insulation organic film having
a wiring pattern on one surface and an adhesive layer on another principal
surface, respectively.
The fifth aspect of the present invention is to provide a thin film wiring
material comprising an insulation organic film having a wiring pattern
layer on one surface and an adhesive layer on the other principal surface.
The sixth aspect of the invention is to provide a method for producing the
thin film wiring material of the fifth aspect of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A, 1A', 1B, 1C, 1D, 2A-2C and 3A-3C show sequence of the steps
according to embodiments of the present invention and FIGS. 4A-4F show
sequence of steps according to a conventional method, where the reference
numeral 1 stand for an insulation organic film, 2 for a wiring pattern, 2'
for a metallic foil, 3 for a substrate, 4 for an adhesive layer, 5 for a
through-hole, 6 for a resist, 7 for a wiring pattern, 8 for a provisional
substrate (metal, glass), and 9 for an eutectic solder.
DETAILED DESCRIPTION OF THE DRAWINGS
FIGS. 1A to 1D show one embodiment given in Example 1.
FIG. 1A shows a metal-lined film 1, prepared by applying a varnish to a
metallic foil 2', followed by heating to cure the varnish to form a film
1.
FIG. 1A' shows a laminate prepared by forming a patterned resist (not shown
in the drawing) on the open side of the metallic foil 2', followed by
light exposure, development etching, whereby a wiring pattern 2 is formed
from the metallic foil 2' on the film 1, then plasma treating the other
side of the film 1 and placing the plasma-treated side of the film onto a
substrate 3 having a wiring pattern 12 on the surface through an adhesive
layer 4, while aligning the wiring pattern 2 to the wiring pattern 12
(circuit) by a mask aligner, followed by tentative adhesion by an
ultraviolet lamp or the like or by partially heated pressing, and then by
heated pressing in an autoclave to bond the film 1 to the substrate 3.
FIG. 1B shows through-holes 5 made at desired positions by forming a mask
pattern thereon by mask imaging process or contact mask process using a
metallic or dielectric mask or the like, while positioning the mask
pattern to other positions than those for the desired through-holes
followed by irradiation of excimer laser, and formation of a resist
pattern 6 for chemical (electroless) plating, followed by light exposure
and development, while positioning the resist according to a pattern mask
so as to prevent chemical (electroless) plating on plating-unwanted
positions.
FIG. 1C shows platings 7 provided in the through-holes 5 by chemical
plating to make the wiring pattern 2 on the film 1 and the wiring pattern
12 on the substrate conductive to each other, where the thickness of the
platings 7 can be adjusted as desired. After the electroless plating, the
resist 6 is removed.
FIG. 1D shows a thin film multilayer substrate obtained by repetitions of
the foregoing steps.
FIGS. 2A to 2C show another embodiment of the present invention.
FIG. 2A shows a thin film multilayer laminate with a desired number of
layers formed on a provisional substrate 8 of glass or the like in the
same manner as given in FIGS. 1A to 1D.
FIG. 2B shows the thin film multilayer laminate freed from the provisional
substrate 8.
FIG. 2C shows the thin film multilayer laminate of FIGS. 2B placed on a
substrate 3 having eutectic solders 9 as a wiring pattern while
positioning the laminate and the substrate 2 to make the wirings 7
conductive with the eutectic solders 9 on the substrate 3, followed by
heated pressing. Owing to the provision of the adhesive layers 4 uniform
pressing can be obtained, and also the deviation between the thin film
multilayer laminate and the substrate can be prevented at the same time.
FIGS. 3A to 3C shows other embodiment of the present invention.
FIG. 3A shows two thin film multilayer laminates each with desired number
of layers and varied wiring patterns formed each on a provisional
substrate 8 in the same manner as in FIG. 2A.
FIG. 3B shows the thin film multilayer laminates freed form the provisional
substrate 8 in the same manner as in FIG. 2B.
FIG. 3C shows the thin film multilayer laminates of FIG. 3B integrated into
one body through eutectic solders 9 therebetween on a common substrate 3
having eutectic solders 9 as a wiring pattern while positioning the
laminates and the substrate 3 to make wirings 7 of both laminates
conductive with the eutectic solders 9 on the substrate, followed by
heated pressing.
The insulation organic films for use in the present invention are polymer
films with such characteristics as a heat resistance (pyrolysis beginning
temperature) of 350.degree. to 550.degree. C., a dielectric constant cf
3.5 to 2.2, a flame retardance (according UL-94 standard) of V-0 or V-1, a
thermal expansion coefficient of not more than 2.0.times.10.sup.5
/.degree.C., and a thickness of 1 to 100 .mu.m. Examples of effective
polymer films include polyimide, polyetherimide, polyesterimide,
polyamideimide, polyether ether ketone, polysulfone, polycarbonate, liquid
crystal polymer and polyfluorocarbon. Polyimide film is especially
effective for satisfying the above-mentioned characteristics.
Polyamic acids are generally used as the polyimides or precursors thereof
in the present invention. Furthermore, esterified amic acids and reaction
products of carboxylic dianhydrides with diisocyanates can be also used.
As skeletons thereof, for example, polymers of aromatic aminocarboxylic
acids and those obtained from aromatic diemines or diisocyanates and
aromatic tetracarboxylic acids as starting materials can be used.
The precursors of polyimides can be obtained by homopolymerization of
aromatic aminodicarboxylic acid derivatives or reaction of aromatic
diemines or aromatic isocyanates with tetracarboxylic acid derivatives.
The tetracarboxylic acid derivatives include, for example, esters,
carboxylic dianhydrides and acid chlorides. Carboxylic acid dianhydrides
are preferred from the viewpoint of synthesis.
The synthesis reaction is generally carried out at -20.degree. to
200.degree. C. in a solvent such as N-methylpyrrolidone,
dimethylformamide, dimethytacetamide, dimethylsulfoxide, dioxanet
tetrahydrufuran, or acetophenone.
Examples of the aminodicarboxylic acid derivatives include 4-aminophthalic
acid, 4-amino-5-methylphthalic acid, 4-(p-anilino)phthalic acid,
4-(3,5-dimethyl-4-anilino)phthatic acid, and esters, acid anhydrides and
acid chlorides thereof.
The aromatic diamines for use in the present invention include, for
example, those having a linear conformation such as p-phenylenediamine,
2,5-diaminotoluene, 2,5-diaminoxylene, diaminodurene
(2,3,5,6-tetramethylphenylenediamine), 2,5-diaminobenzotrifluoride,
2,5-diaminoanisole, 2,5-diaminoacetophenone, 2,5-diaminobenzophenone,
2,5-diaminodiphenyl, 2,5-diaminofluorobenzene, benzidine, o-tolidine,
m-tolidine, 3,3',5,5'-tetramethytbenzidine, 3,3'-dimethoxybenzidine,
3,3'-di(trifluoromethyl)benzidine, 3,3'-diacetylbenzidine,
3,3'-difluorobenzidine, octafluorobenzidine, 4,4'-diaminoterphenyl, and
4,41-diaminoquaterphenyl; m-phenylenediamine, 4,4'-diaminodiphenylmethane,
1,2-bis(anilino)ethane, 4,4'-diaminodiphenyl ether, diaminodiphenyl
sulfone, 2,2'-bis(p-aminophenyl)propane,
2,2'-bis-(p-aminophenyl)hexafluoropropane,
3,3'-dimethyl-4,4'-diaminodiphenyl ether,
3,3'-dimethyl-4,4'-diaminodiphenylmethane, diaminotoluene,
diaminobenzotrifluoride, 1,4-bis(p-aminophenoxy)benzene,
4,4'-bis(p-aminophenoxy)-biphenyl, hexafluoropropane,
2,2'-bis{4-(p-amino-phenoxy)phenyl}propane,
2,2'-bis{4-(m-aminophenoxy)-phenyl}proprane,
2,2'-bis{4-(p-aminophenoxy)phenyl}-hexafluoropropane,
2,2'-bis{4-(m-aminophenoxy)phenyl}-hexafluoropropane,
2,2'-bis{4-(p-aminophenoxy)-3,5dimethylphenyl}hexafluoropropane,
2,2'-bis{4-(p-amino-phenoxy)-3,5-ditrifluoromethylphenyl}hexafluoropropane
, p-bis(4-amino-2-trifluoromethylphenoxy)benzene,
4,4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl,
4,4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl sulfone,
4,4'-bis(3-amino-5-trifluoromethylphenoxy)-biphenyl sulfone,
2,2'-bis{4-(p-amino-3-trifluoromethylphenoxy)phenyl}hexafluoropropane,
diaminoanthraquinone, 4,4'-bis(3-aminophenoxyphenyl)diphenyl sulfone,
1,3-bis(anilino)hexafluoropropane, 1,4-bis(anilino)-octafluorobutane,
1,5-bis(anilino)decafluoropentane, 1,7-bis(anilino)tetradecafluoroheptane,
and diaminosiloxanes represented by the following formula:
##STR1##
wherein R.sub.4 and R.sub.6 each represents a monovalent organic group,
R.sub.5 and R.sub.7 each represents a divalent organic group, and p and q
each represents an integer of more than 1. Diisocyanate compounds thereof
can also be used.
The tetracarboxylic acid derivatives for use in the present invention
include, for example, pyromellitic acid, methylpyromellitic acid,
dimethylpyromeltitic acid, di(trifluoromethyl)pyromellitic acid,
3,3',4,4'-biphenyltetracarboxylic acid,
5,5'-dimethyl-3,3',4,4'-biphenyltetracarboxylic acid,
p-(3,4-dicarboxyphenyl)benzene, 2,3,3',4-tetracarboxydiphenyl,
3,3',4,4'-tetracarboxydiphenyl ether, 2,3,3',4-tetracarboxydiphenyl ether,
3,3',4,4'-tetracarboxybenzophenone, 2,3,3',4-tetracarboxybenzophenone,
2,3,6,7-tetracarboxynaphthalene, 1,4,5,7-tetracarboxynaphthalene,
1,2,5,6-tetracarboxynaphthalene, 3,3',4,4'-tetracarboxydiphenylmethane,
2,3,3',4-tetracarboxydiphenylmethane, 2,2-bis(3,4-dicarboxyphenyl)propane,
2,2-bis(3,4-dicarboxyphenyl)hexafluorepropane,
3,3',4,4'-tetracarboxydiphenyl sulfone, 3,4,9,10-tetracarboxyperlyene,
2,2'-bis{4-(3,4-dicarboxyphenoxy)-phenyl}propane,
2,2'-bis{4-(3,4-dicarboxyphenoxy)phenyl}hexafluoropropane,
butanetetracarboxylic acid, and cyclopentanetetracarboxylic acid. Acid
anhydrides, acid chlorides and esters thereof can also be used.
More specifically, polyimide films containing repeated structures
represented by the following formula are especially effective.
##STR2##
wherein X represents an aromatic diamine residue.
In the present invention, the polyimides not completely imidized are
preferable from the viewpoint of adhesiveness. A polyimide precursor film
can be obtained by uniformly applying a solution of the polyimide
precursor, for example, by spin coating and drying preferably at about
50.degree. to 250.degree. C. In case of using the polyimide precursor
film, it is desirable to heat the film at a high temperature to convert it
to polyimide or to dip the film in a solution of an imidizing agent to
imidize it. When the imidization is carried out by heating, it is
desirable to heat the film to at least the glass transition temperature of
the polyimide produced.
In the present invention, when diamines having a linear conformation are
used as a diamine component and pyromellitic acid derivatives or biphenyl
tetracarboxylic acid derivatives are used as tetracarboxylic acids,
rodlike polyimides low in the thermal expansion coefficient can be
obtained with such advantages that Si chips can be directly attached.
In the present invention, the film may be formed in advance and then a
conductive film may be formed thereon, but it is also possible to coat a
conductor such as a metallic foil with a varnish, cure the varnish and
then form a conductor pattern. In that case, adhesiveness of polyimide to
various substrate materials will be a problem. The surface of inorganic
substrate material may be roughened or a surface treating agent such an a
silane coupling agent, a titanate coupling agent, an aluminum alcoholate,
an aluminum chelate, a zirconium cholate, or an aluminum acetylacetone may
be added to the polyimide.
Powders of inorganic materials, organic materials or metals or fibers may
also be added to the polyimide to lower the thermal expansion coefficient,
or increase the modulus or control the flowability.
In the present invention the insulation organic film laminated with a
metallic foil on one surface by an adhesive, followed by pattern formation
or a film of the above-mentioned polymer formed by directly applying the
polymer to a metallic foil and then forming a wiring pattern thereon can
be used. In order to reduce the thermal stress developed at the interface
between the insulation organic film and a metal such as copper as a wiring
pattern material it is important that the insulation organic film has a
heat resistance (pyrolysis beginning temperature) of at least 350.degree.
C., a dielectric constant of 3.5 to 2.2 and a thermal expansion
coefficient of 2.0.times.10.sup.-5 /.degree.C. or less.
In the present invention, a wiring pattern on one surface of the insulation
organic film can be formed by etching an insulation organic film having a
metallic foil on one surface or by conducting sputtering or plating on one
surface of the organic film. In that case, light exposure, development and
heat treatment are carried out with a photosensitive material and
thereafter conduction treatment is carried out by plating, etc. This
method is effective for formation of pattern of 40 .mu.m or less
especially 10 to 40 .mu.m, in both wiring line thickness and wiring line
width. Furthermore, the resulting wiring pattern is distinguished in the
smoothness and processability.
For the adhesive layer, for example, a half-cured polyimide film of
polyimide, a heat-curable film composed of polyimide and polymaleimide,
silicone resin, epoxy resin and a thermotropic liquid crystal film having
polymerization-reactive functional groups, a film coated with an adhesive
on the surface, nonwoven fabrics impregnated with an adhesive, glass
cloth, reinforcing fibrous materials such as fluorine-based fibers, and a
varnish type adhesive can be used. Especially, an adhesive containing an
ether bismaleimide compound represented by the following formula is
effective for reducing the thermal stress, decreasing the dielectric
constant and maintaining the heat resistance and adhesiveness.
##STR3##
wherein R.sub.1 is H, a lower alkyl group or a lower fluoroalkyl group;
R.sub.2 is H, a lower alkyl group or a lower fluoroalkyl group, m is an
integer of 1 to 4; and R.sub.3 and R.sub.4 are CH.sub.3 or CF.sub.3 and
may be identical with or different from each other.
Method for producing a thin film multilayer wiring board according to the
present invention will be explained below.
After checking a wiring pattern formed on one surface of an organic film,
the film is subjected to positioning to a ceramics substrate or the like
and is bonded to the substrate by a vacuum press or in an autoclave.
Bonding temperature is 300.degree. C. or lower, preferably 250.degree. C.
or lower. Above 300.degree. C., occurrence of warping of the substrate or
poor dimensional stability during the lamination is a problem.
Through-holes can be formed, for example, by excimer laser, CO.sub.2 gas
laser, EB (electron beam), plasma etching, or photoetching. In the present
invention, it is desirable to make through-holes by a laser beam, thereby
improving the productivity. Furthermore, chemical plating or
electroplating can be used to make the through-holes conductive. Line
width and line thickness of the pattern must have a specific size from the
viewpoint of characteristic impedance and higher density, and the
thickness of pattern must be controlled at the same time as the
through-holes are made conductive. In the present invention, both line
thickness and line width are preferably 40 .mu.m or less, more preferably
10 to 40 .mu.m. Furthermore, filling of through-holes with a conductive
paste or a low melting metal such as a soldering material can be also used
as a means of making the through-holes conductive.
In the present invention, multilayer structure is formed either by
successfully laminating organic films having a wiring pattern on the
surface on the surface of a substrate or by sequentially laminating a
given number of organic films on a provisional substrate such as a metal
plate and thereafter separating the laminate from the provisional
substrate, and bonding the separated laminate to a surface of a substrate
of, e.g. ceramics as shown in FIGS. 2A to 2C and FIGS. 3A to 3C. In that
case, positioning accuracy is very important. A high positioning accuracy
can be obtained by providing an organic film on a substrate by suction
through an adhesive material in a similar apparatus to a mask aligner and
then bonding the film to the substrate by pressing after making the
adhesive material adhesive by high-frequency heating or laser heating and,
in case of using a photosensitive material, by exposing the photosensitive
material to light, thereby once lightly bonding the organic film to the
photosensitive material, followed by lamination on the substrate in the
same manner as above. Full curing can be carried out at that time or later
after lamination of all the layers.
PREFERRED EMBODIMENTS OF THE INVENTION
The present invention will be explained in detail below, referring to
examples.
EXAMPLE 1
A copper foil (12-.mu.m thick) 2' was coated with N-methyl-2-pyrrolidone
varnish of polyamic acid obtained by reacting p-phenylenediamine,
pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride
in a molar ratio of 1:0.5:0.5 and the coated copper foil 2' was heated at
120.degree. C. for 30 minutes and then at a temperature of 120.degree. C.
to 400.degree. C. over a period of 2 hours in a nitrogen gas containing 2%
by volume of hydrogen and further heated at 400.degree. C. for 10 minutes
to obtain a film 1 provided with a copper film on one side. The resulting
polyimide had a thermal expansion coefficient of 1.0.times.10.sup.-5
/.degree.C., a dielectric constant of 3.5, a heat resistance (pyrolysis
beginning temperature) of 510.degree. C., and a thickness of 25 .mu.m. The
film 1 was then subjected to patterning by photolithography to form a
wiring pattern 2. Then, a photo-curable methacrylate ester-terminated
silicone resin film was formed as an adhesive material to a thickness of
about 20 .mu.m on both sides of another polyimide film for an adhesive
layer 4 having a thermal expansion coefficient of 1.0.times.10.sup.-5
/.degree.C., prepared from p-phenylenediamine and
3,3',4,4'-biphenyitetracarboxylic dianhydride as raw materials. The
polyimide surface of the polyimide film 1 having the wiring pattern 2
formed above was subjected to a plasma treatment and the thus
plasma-treated polyimide film was placed on a mullite substrate 3 having a
thermal expansion coefficient of 6.times.10.sup.-6 /.degree.C. through the
adhesive layer 4 while making positioning to align the wiring pattern 2 to
the wiring pattern 12 (circuit) on the substrate 3 by a mask aligner,
followed by exposing the laminate to ultraviolet rays, thereby making
bonding therebetween. Then, the laminate was heated and bonded under
pressure in an autoclave at 150.degree. C. for 5 hours (FIG. 1A'). Then,
through-holes 5, about 40 .mu.m in diameter, were made at the
predetermined positions through the resist pattern 6 by excimer laser
(FIG. 1B) and chemically plated to make the through-holes 5 conductive
with the wiring pattern (circuit) 12 on the mullite substrate 3 (FIG. 1C),
and simultaneously a chemically plated wiring pattern 7, 40 .mu.m in line
width and 35 .mu.m in line thickness, was obtained. The same procedure as
above was repeated to form a multilayer wiring board in six layers (FIG.
1D). The desired thin film multilayer wiring board was thus obtained.
EXAMPLES 2 and 3
Thin film multilayer wiring boards were obtained in the same manner as in
Example 1 except that a polyimide film clad with a copper foil (18-.mu.m
thick) by an acrylic adhesive and a polyether imide film clad with a
copper foil (18-.mu.m thick) by an epoxy adhesive were used as the
insulation organic films.
EXAMPLE 4
An adhesive film was obtained from N,H'-(4,4'diphenylmethane)bismaleimide
and a polyimide prepared from p-phenylene diamine and
3,3',4,4'-biphenyltetracarboxylic dianhydride. Thin film multilayer wiring
boards were prepared in the same manner as in Example 1 except that the
above adhesive films were used, respectively, and heat cured by a vacuum
press at 250.degree. C. for 1 hour.
EXAMPLE 5
An adhesive film was obtained from
2,2-bis{4-(4-maleimidophenoxy)phenylpropane and a polyimide prepared from
p-phenylene diamine and 3,3',4,4'-bisphenyltetracarboxylic dianhydride. A
thin film multilayer wiring board was prepared in the same manner as in
Example 1 except that the above adhesive film was used and heat cured by a
vacuum press at 230.degree. C. for 1 hour.
EXAMPLE 6
A thin film multilayer wiring board was obtained in the same manner as in
Example 1 except that polyimide-based cover coat ink (SPI-200, trademark
of a product made by Shinnittetsu Chemical Co., Ltd., Japan) as an
adhesive material was applied to the substrate and dried at 130.degree. C.
for 3 minutes and the resulting substrate was clad with the film having a
wiring pattern, followed by heat curing at 200.degree. C. for 5 minutes by
a vacuum press.
EXAMPLE 7
A thin film multilayer wiring board was obtained in the same manner as in
Example 2 except that a flat sheet, prepared by subjecting to plasma
treatment the surface of a polyimide of low thermal expansion (polyimide
having a thermal expansion coefficient of 1.0.times.10.sup.-5 /.degree.C.,
a dielectric constant of 3.5 and a heat resistance of 510.degree. C.,
prepared from p-phenylenediamine and 3,3',4,4'-biphenyltetracarboxylic
dianhydride) and then to a treatment with a colloidal Pd catalyst
suspension, then to coating with a photosensitive polyimide, followed by
light exposure, development and heating, and then to forming of a wiring
pattern by chemical plating and electroplating, was used.
EXAMPLE 8
A thin film multilayer wiring board was obtained in the same manner as in
Example 1 except that an organic film having a copper foil, 18 .mu.m
thick, on one side and a polyimide adhesive on another side was used and
heating under pressure was carried out at 250.degree. C. for 30 minutes.
EXAMPLE 9
As an organic film, a polyimide film having a copper foil, 12 .mu.m thick,
the polyimide film was a dehydration condensation reaction product of
p-phenylenediamine and 3,3',4,4'-biphenyltetracarboxylic dianhydride and
had a thermal expansion coefficient of 1.0.times.10.sup.-5 /.degree.C. a
heat resistance of 510.degree. C., and a thickness of 25 .mu.m) was
subjected to patterning by photolithography to form a wiring pattern, 20
.mu.m in line width. The polyimide surface of the polyimide film was
subjected to a plasma treatment and was subjected to positioning to a
mullite substrate having a thermal expansion coefficient of
6.times.10.sup.-6 /.degree.C. through the following adhesive material (A)
by a mask aligner, followed by lamination aid bonding by exposure to
ultraviolet rays. Then, through-holes, about 20 .mu.m in diameter, were
made at the predetermined positions by excimer laser and were made
conductive by chemical plating and a pattern, 25 .mu.m in line thickness,
was formed. This procedure was repeated through the adhesive material to
form a multilayer wiring board with 26 layers, which was finally heat
cured at 150.degree. C. for 5 hours to obtain the desired thin film
multilayer wiring board.
Preparation of adhesive material (A)
1.0 mole of p-phenylenediamine was reacted with 1.0 mole of
3,3',4,4'-biphenyltetracarboxylic dianhydride in N-methylpyrrolidone (NMP)
to obtain a 3% solution of polyamic acid. with a structural unit
(polyimide precursor) represented by the following formula. To the
solution was added a 3% solution of N,N'-(4,4'-diphenyl ether)bismaleimide
in NMP.
##STR4##
Then, the polyamic acid and bismaleimide mixed solution was applied to a
glass substrate and then dehydration condensation reaction was carried out
at 350.degree. C. for 5 hours to obtain a polyimide film (A-imide), 20
.mu.m thick, with a thermal expansion coefficient of 1.0.times.10.sup.-6
/.degree.C. and the following structural unit:
##STR5##
Then, a silicone resin having terminal methacrylate groups was applied to
both sides of the above polyimide film to a thickness of about 20 .mu.m
and dried to form an adhesive layer.
EXAMPLE 10
As an organic film, a polyimide film having a copper foil, 12 .mu.m thick,
on one side (the polyimide was a dehydration condensation reaction product
of 0.6 moles of p-phenylenediamine and 0.4 moles of 4,4'-diaminodiphenyl
ether as a diamine component with 1.0 mole of
3,3',4,4'-biphenyltetracarboxylic dianhydride and had a thermal expansion
coefficient of 1.8.times.10.sup.-5 /.degree.C., a dielectric constant of
3.8, a heat resistance of 480.degree. C., and a thickness of 25 .mu.m) was
subjected to patterning by photolithography to form a wiring pattern, 20
.mu.m in width. Then, the polyimide surface of the polyimide film was
subjected to a plasma treatment and to positioning to a glass substrate
having a thermal expansion coefficient of 4.0.times.10.sup.-5 /.degree.C.
through the following adhesive material (B) by a mask aligner, followed by
lamination and bonding. Then, through-holes, about 20 .mu.m in diameter,
were made at the predetermined positions by excimer laser and made
conductive by chemical plating and a pattern, 25 .mu.m in line thickness,
was formed. This procedure was repeated through the adhesive material to
form a multilayer wiring board with 35 layers, which was finally heat
cured at 200.degree. C. for 10 hours to obtain the desired thin film
multilayer wiring board.
Preparation of adhesive material (B)
Both sides of the polyimide film (A-imide) used in preparation of adhesive
material (A) was coated with a solution in NMP containing 1% by weight of
a mixture consisting of the following addition reaction type unsaturated
imide:
##STR6##
and a phenoxy resin (PKHH, trademark of a product made by Union Carbide
Corp., USA) in a ratio by weight of the former to the latter of 8.5/1.5 to
a thickness of 5 .mu.m and dried.
EXAMPLES 11 and 12
Example 10 was repeated except that the following adhesive material (C) and
the following adhesive material (D) were used.
Preparation of adhesive material (C)
Both sides of the polyimide film (A-imide) used in preparation of adhesive
material (A) was coated with a 2% solution in NMP containing 2% by weight
of a mixture consisting of N,N'-(4,4'-diphenylmethane)bismaleimide and
polyvinyl butyral in a ratio by weight of the former to the latter of
8.0/2.0 to a thickness of 15 .mu.m and dried.
Preparation of adhesive material (D)
Solution containing 1% by weight of
2,2-bis{4-(4-maleimidephenoxy)phenyl}hexafluoropropane in NMP was applied
to one side of the polyimide (A-imide) used in preparation of the adhesive
material (A) and a solution containing 1% by weight of a mixture
consisting of 2,2-bis{(4-4-maleimidephenoxy)phenyl}hexafluoropropane and
phenoxy resin PKHH in a ratio by weight of the former to the latter of
8.5/1.5 was applied to another side and dried.
Comparative Example (Conventional method)
As shown in FIG. 4, a polyimide varnish was applied to ceramics substrate 3
having a wiring pattern and heat treated at 370.degree. C. for 1 hour to
form potyimide insulation layer 10 (FIG. 4A). Then, resist pattern 12 was
formed on the desired portion and through-holes 11 were formed by etching
(FIG. 4B). Then, a wiring metal was deposited by sputtering and then a
resist pattern was provided on the portion which was to be a wiring and
unnecessary metal was etched off to form a wiring pattern 13 (FIG. 4C). A
polyimide varnish was further applied to the wiring pattern and heat
treated to form an insulation layer, and at that time grinding was carried
out for flatting the surface (FIG. 4D.fwdarw.FIG. 4E). This procedure was
repeated to form a multilayer wiring board with mix layers (FIG. 4F) and
the desired thin film multilayer wiring board was obtained.
Yield, production time and fluctuation in the interlayer thickness of thin
film multilayer wiring boards prepared in Examples 1 to 8 and Comparative
Example are shown in the following Table.
TABLE
__________________________________________________________________________
Compa-
rative
Example
(Conven-
Example tional
Item 1 2 3 4 5 6 7 8 method)
__________________________________________________________________________
Yield of thin
>60
>60 >60
>60 >60
>60 >60
>60 <10
film multi-
layer wiring
board
Production
<30
<30 <30
<30 <30
<30 <30
<30 100
time* of thin
film multi-
layer wiring
board
Fluctuation
Sub-
Sub-
Sub-
Sub-
Sub-
Sub-
Sub-
Sub-
Much
in inter-
stan-
stan-
stan-
stan-
stan-
stan-
stan-
stan-
fluc-
layer thick-
tially
tially
tially
tially
tially
tially
tially
tially
tuated
ness of thin
none
none
none
none
none
none
none
none
film multi-
layer wiring
board
__________________________________________________________________________
*Relative to the conventional method as 100.
According to the present method for making a thin film multilayer wiring
substrate of highly multiple layers, use of an organic film on which a
wiring pattern is formed in advance facilitates to check the pattern and
gives a remarkable effect on the yield and reliability. The thin film
multilayer wiring board of the present invention is useful for packages
and module substrates for large-scale computers and supercomputers.
Top